In the manufacture of corrugated boxes, or boxes fabricated from other paper materials, blank sheets of the material are cut to size on a cutting machine. Glue is then applied to the board upon exit from the cutting machine by means of a suitable glue dispenser, usually glue wheels or extrusion nozzles. The applied glue forms linear beads in prescribed positions and of predetermined lengths on the board.
The board exits the cutter at a speed sufficiently high that visual verification of the proper application of the glue is not possible. Errors in glue application frequently go undetected until many scrap boards are produced. Common errors include the application of too much or too little glue, glue application in the wrong areas of the board, and glue splatters which occur outside of the area intended to be glued.